Because in the data, Germany did not exist before 1990 and there is a significant population that were born in East or West. It doesn't seem like the tool actually uses the differences but there is likely a difference between life span depending on which side of the Berlin wall you were born on, before and after reunification. The former East Germany is still more economically depressed in comparison to its western counterpart. It's the difference between living in a poor state like Mississippi and a wealthier state like California. Numerous factors like access to better food and healthcare play into this but the major factor is money. Poorer people usually don't live as long as wealthier ones.